The present invention relates generally to a system and method used in conjunction with an implantable medical device. More specifically, the present inventing relates to powering an implantable medical device through use of a difference in temperature between locations within a patient.
Implantable medical device systems known in the art comprise several components, including an implantable medical device, such as a pacemaker or defibrillator, pacing and/or sensing leads, and a programmer. The leads connect the implantable medical device to the heart of a patient.
An implantable medical device, such as a pacemaker or a defibrillator, is a microprocessor-based component and commonly stores a variety of different types of diagnostic data which assists a clinician or a physician in evaluating both the operation of the patients heart and the operation of the implanted medical device. The specific diagnostic data is stored by the implantable medical device within the microprocessor and includes a variety of information, including a real-time event recording of pacing events. An implantable medical device includes numerous electrical components which must be powered by a power source.
The programmer of the implantable medical device system is located outside of the patient, such as at a hospital or clinic. The programmer can be connected to the implantable medical device via radio frequency (RF) connections. The programmer provides multiple functions, including (a) assessing lead performance during a pacemaker or defibrillator implantation, (b) programming the implantable medical device, and (c) receiving feedback information from the implantable medical device for use by the operator.
An analyzer, which is sometimes a sub-component of the programmer and sometimes an individual component is a microprocessor-base component designed to assess the electrical performance of a pacing lead system used in conjunction with an implantable medical device system. The analyzer utilizes the programmer as a control and display platform.
Pacemakers and defibrillators utilize an internal power supply, such as a battery, to generally power the device, and to specifically power individual electrical components of the device. Prior art batteries of a pacemaker or defibrillator have a fixed life span. For example, most present-day power sources of implantable medical devices have a life span in the range of 4 to 8 years. There is, therefore, a need for a power source used in conjunction with an implantable medical device which will exceed the life span of prior art power sources.
Thermoelectricity is a term that describes the electricity generated by applying heat to the junction of two different materials, such as metals or semiconductors. If two wires of different materials are joined at their ends, and one end is at a higher temperature than the other, a voltage difference will arise, and an electrical current will flow. The voltage difference varies in direct proportion to the temperature difference. This proportionality is used in a device called a thermocouple. Using semiconductor materials instead of metals can increase the current within the thermocouple. In addition, using multiple thermocouples in series can increase voltage.
It is known within the medical industry that there is a temperature difference between a human body and its external surroundings. Recent technology has utilized this temperature difference in order to provide power to electrical and electromechanical components of a device, such as a wristwatch, through use of a thermocouple effect. The patents listed below in Table 1 discuss the concept of utilizing a temperature difference between a human body and its surroundings to generate a voltage which can thereby be used to power a device such as a wrist watch.
Similar to the recognition of the difference in temperature between a human body and its surroundings, is the recognition that there are differences in temperatures within a human body. For example, there can be up to a 2xc2x0 C. temperature difference between internal organs or passageways and their surroundings. It is, therefore, desirous to utilize the temperature difference within a human body to power an implantable medical device, such as a pacemaker, a defibrillator, or any other medical devices discussed in U.S. Pat. No. 5,891,180 to Greeninger et al, hereby incorporated by reference.
The present invention overcomes the disadvantages of the prior art by providing a method of and a system for supplying power to an implantable medical device within a patient via temperature differentials within the patient.
The present invention has certain objects. That is, the present invention provides solutions to certain problems existing in the prior art such as: (a) an inability to utilize a temperature differential between two leads within a body to provide power to an implantable medical device; (b) an inability to utilize a temperature differential between a first lead position within a lung of a patient and a second lead positioned outside the lung of the patient to provide power to an implantable medical device; (c) an inability to utilize a temperature differential between a first lead positioned within a liver of a patient and a second lead positioned outside the liver of the patient to provide power to an implantable medical device; (d) an inability to utilize a temperature differential between a first lead position within a blood passageway of the body and a second lead positioned outside of the blood passageway to provide power to an implantable medical device; (e) an inability to provide voltage to a storage element, such as a battery or a capacitor, thereby producing a power source for an implantable medical device; (f) an inability to utilize a thermal device and a DC-DC converter to generate a voltage capable of powering an implantable medical device; and (g) an inability to provide the necessary power to an implantable medical device, regardless of a temperature differential between two leads positioned within the patient.
A system and method of the present invention provides certain advantages including: (a) the ability to utilize a temperature differential between two leads within a body to provide power to an implantable medical device; (b) the ability to utilize a temperature differential between a first lead position within a lung of a patient and a second lead positioned outside the lung of the patient to provide power to an implantable medical device; (c) the ability to utilize a temperature differential between a first lead positioned within a liver of a patient and a second lead positioned outside the liver of the patient to provide power to an implantable medical device; (d) the ability to utilize a temperature differential between a first lead position within a blood passageway of the body and a second lead positioned outside of the blood passageway to provide power to an implantable medical device; (e) the ability to provide voltage to a storage element, such as a battery or a capacitor, thereby producing a power source for an implantable medical device; (f) the ability to utilize a thermal device and a DC-DC converter to generate a voltage capable of powering an implantable medical device; and (g) the ability to provide the necessary power to an implantable medical device, regardless of a temperature differential between two leads positioned within the patient.
The system and method of the present invention has certain features, including a first and a second thermocouple lead for positioning within a patient in order to generate a voltage based upon a temperature difference between the two leads. The first and second thermocouple lead of the present invention can be positioned within the patient at numerous locations, as long as there is a temperature differential between the two leads. The temperature difference serves as an input into a thermoelectric device. The thermoelectric device converts the temperature differential between the first and second thermocouple leads to a voltage. Another feature of the present invention is a DC-DC converted connected to the thermoelectric element for increasing the voltage by producing an increased voltage. A further feature of the present invention of the present invention is a storage element connected to the DC-to-DC converter for receiving the increased voltage. The storage element is also connected to the implantable medical device, thereby providing power to the implantable medical device. The storage element is capable of receiving and maintaining an excess amount of electrical energy such that the storage element can provide continuous power to the implantable medical device even in the absence of a temperature differential between the first and second thermocouple leads. Conversely, another feature of the present invention is the ability to supplement a separate, primary power system.